package cnpm02.j2ee.group3.logic.utils;

import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class DESUtil {
	private Cipher ecipher;
    private Cipher dcipher;
    private static SecretKey key;
    
    private DESUtil(SecretKey key) {
        try {
            ecipher = Cipher.getInstance("DES");
            dcipher = Cipher.getInstance("DES");
            ecipher.init(Cipher.ENCRYPT_MODE, key);
            dcipher.init(Cipher.DECRYPT_MODE, key);

        } catch (javax.crypto.NoSuchPaddingException e) {
        } catch (java.security.NoSuchAlgorithmException e) {
        } catch (java.security.InvalidKeyException e) {
        }
    }

    public static DESUtil getInstance() {
		try {
			key = KeyGenerator.getInstance("DES").generateKey();
			return new DESUtil(key);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return null;
    }
    
    public static DESUtil getInstance(SecretKey key) {
    	return new DESUtil(key);
    }
    
    public String encrypt(String str) {
        try {
            // Encode the string into bytes using utf-8
            byte[] utf8 = str.getBytes("UTF8");

            // Encrypt
            byte[] enc = ecipher.doFinal(utf8);

            // Encode bytes to base64 to get a string
            return new sun.misc.BASE64Encoder().encode(enc);
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        }
        return null;
    }

    public String decrypt(String str) {
        try {
            // Decode base64 to get bytes
            byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

            // Decrypt
            byte[] utf8 = dcipher.doFinal(dec);

            // Decode using utf-8
            return new String(utf8, "UTF8");
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch (java.io.IOException e) {
        }
        return null;
    }
    
   	public SecretKey getKey() {
		return key;
	}

	//Test
    public static void main(String...strings) throws Exception {
    	DESUtil u = DESUtil.getInstance();
    	DESUtil u1 = DESUtil.getInstance();
    	String encryptedStr = u.encrypt("binh"); 
    	System.out.println(encryptedStr);
    	System.out.println(u1.decrypt(encryptedStr));
    }
}
